Commercial bakeries often package baked bread in an overwrap, which is a plastic sheet wrapper that contains the bread. This overwrap may be the sole airtight packaging for the bread or the bread and its overwrap may be bagged, for example within a plastic bag tied with a twist tie or a clip closure.
A commonly used bread overwrap machine has been manufactured by many corporations such as AMF Incorporated. As shown in FIG. 1, such a bread overwrap machine 10 may, for example, be located in a bakery line 12 after a bread slicer 13 and before a bagger 14. The bread overwrap machine 10 typically has a crossfeed conveyor 16 that picks up individual loaves of bread from the end 15 of a conveyor from the bread slicer 13 and transports them, one loaf at a time, in an end to end (heel to heel) orientation. Each loaf is transported by the crossfeed conveyor in a pocket, formed by a pair of spaced apart flight bars, that moves the loaf from the pick up point 15 to a position 18 in the overwrap machine 10, where it is pushed by a pusher bar onto a reciprocating lifting table. The lifting table moves between a lower position where it receives the loaf of bread, to an upper position where the loaf of bread is removed from the lifting table, at which point the lifting table returns to its lower position. The lifting table, as it lifts the loaf from the lower position to the upper position, lifts the loaf through a web of overwrap material (which is typically a transparent polypropylene film) causing the film to wrap around the loaf of bread, and creates a folds in the film at the end of the loaf. A knife cuts the film as the lifting table reaches its upper position, where the loaf is pushed by an overhead conveyor. The loaves of bread are conveyed laterally through a sealing line such that the folded wrap at the ends of the loaves is sealed by a heated mesh belt or heated rollers along the sides of the conveyor line, as the loaves are conveyed through the machine. A preferred sealing line assembly is disclosed in my U.S. Pat. No. 5,058,362, the disclosure of which I hereby incorporated by reference.
The movement of the various components of the overwrap machine are mechanically coupled together and indexed so that the loaves of bread are delivered one at a time to the lifting table. In particular, the movement of the crossfeed conveyor is a periodic movement that is indexed to the reciprocating movement of the lifting table, so that each pocket containing a loaf of bread arrives in the correct position for the loaf to be transferred to the lifting table when the lifting table is in its lower position. The indexed movement is obtained by interacting cam elements.
Such overwrap machines are typically are provided with mechanisms for adjusting the distance between the flight bars which form the pockets for receiving the baked bread, so as to accommodate different size bread products in the line. The mechanism includes two side-by-side endless chains, one chain which has affixed to it the leading flight bars of each set of flights forming a pocket, the other chain having affixed to it the trailing flight bars of each set of flights forming a pocket. The distance between the flight bars of each pocket set is adjusted by moving the two chains with respect to each other. Moving one conveyor with respect to the other changes the spacing between each set of flight bars.
Such bread overwrap machines typically have a maximum processing rate of approximately 65 loaves per minute. The overwrap machines can act as a bottleneck in production where the baking equipment is capable of higher throughput rates, such as rates of approximately 100 loaves per minute for a bread slicer.
It would be desirable to improve the processing speeds of overwrap machines to receive the output of a slicer, to thereby maximize the production rate at bakeries where the baking equipment is capable of higher throughput rates than in conventional overwrap machines. It would also be desirable to provide a more flexible control system for the overwrap machine that the limited “on/off” status typically associated with traditional overwrap machines, and to provide for automated adjustment of machine components and automated response to changes in product, machine settings, or bakery line changes.